1. Field of the Invention
The present invention relates to a multi-type air conditioner, and more particularly, to an abnormal state detecting apparatus of a multi-type air conditioner and a method thereof.
2. Description of the Conventional Art
Generally, an air conditioner is an apparatus for controlling the temperature, humidity, the air current, and a clean degree of indoor air for a comfortable indoor atmosphere. According to a construction of units, the air conditioner is largely divided into an integration type air conditioner that an indoor unit and an outdoor unit are mounted in a single case and a separation type air conditioner that a compressor and a condenser are constructed as an outdoor unit and an evaporator is constructed as an indoor unit.
The separation type air conditioner comprises a cooling/heating air conditioner for selectively performing a cooling operation and a heating operation of the air conditioner by switching a flow path of a refrigerant by a flow path switching valve.
Recently, a multi-type air conditioner having a plurality of indoor units for performing a cooling operation or a heating operation according to each space is being increasingly used. The multi-type air conditioner is provided with a plurality of outdoor units respectively having a plurality of compressors in parallel so as to correspond to a driving load of indoor units.
FIG. 1 is a view showing a construction of outdoor units of a multi-type air conditioner in accordance with the conventional art.
As shown, the conventional multi-type air conditioner is provided with a plurality of outdoor units (11a˜11n), and a plurality of indoor units (not shown).
The plural outdoor units respectively comprises a pair of first and second compressors 13a and 13b for compressing a refrigerant, a four-way valve 21 for switching a flow path of the refrigerant, an outdoor heat exchanger 25 for exchanging heat of the refrigerant, and an accumulator 27 for providing a refrigerant of a gaseous state to the first compressor 13a and the second compressor 13b. 
The first compressor 13a and the second compressor 13b are respectively provided with a discharge pipe 15 for discharging a refrigerant at an upper region thereof, and is provided with a suction pipe 17 of which one side is connected to an accumulator 27 in order to suck a refrigerant at a lower region thereof. An oil balancing pipe 19 for uniformly supplying oil to the first compressor 13a and the second compressor 13b is connected between the first compressor 13a and the second compressor 13b. 
The first compressor 13a and the second compressor 13b are provided with an oil separator 31 for separating oil from a refrigerant and a check valve 33 at each discharge side thereof, respectively. The oil separator 31 is provided with an oil recollecting path 35 for recollecting separated oil to each suction side of the first compressor 13a and the second compressor 13b. 
A four-way valve 21 for switching a flow path of a refrigerant is provided at a lower side of the check valve 33. The outdoor heat exchanger 25 is connected to a first port of the four-way valve 21, and the accumulator 27 is connected to a second port of the four-way valve 21. Also, one end of a connection pipe 41 connected to the indoor unit is connected to a third port of the four-way valve 21.
A receiver 37 is provided at one side of the outdoor heat exchanger 25 along a flow direction of a refrigerant. Service valves 43a and 43b are respectively provided at each one side of the receiver 37 and the connection pipe 41. Each one side of the service valves 43a and 43b is connected to a main refrigerant pipe 45 for connecting the outdoor units 11a˜11n one another.
The conventional multi-type air conditioner is provided with a plurality of indoor units (first to Nth indoor unit) and a plurality of outdoor units (first to Mth outdoor unit) connected to one another.
FIG. 2 is a schematic diagram showing a state that plural outdoor units (first to Mth outdoor unit) are connected to plural indoor units (first to Nth indoor unit).
The plural outdoor units are connected to the plural indoor units by a communication wire, and one of the plural outdoor units is operated by a central controller. The outdoor unit operated by the central controller controls other outdoor units and the plural indoor units (first to Nth indoor unit) for a cooling operation or a heating operation.
A user drives the indoor units by using a remote controller, the central controller, etc. of the multi-type air conditioner thusly to check whether a cooling operation of a heating operation of the air conditioner is well performed, thereby checking an abnormal state of the multi-type air conditioner.
However, at the time of installing the plural indoor units and the plural outdoor units of the multi-type air conditioner, an installation inferiority such as an inferior pipe connection, a mis-connection of a communication wire, etc. or a mechanical damage may be generated.
That is, in the conventional multi-type air conditioner, an abnormal state such as an inferior installation or a mechanical damage of the air conditioner is not precisely checked due to a complicated structure of the air conditioner, thereby degrading a function of the air conditioner or causing a mechanical damage of the air conditioner.